Disclosed herein is a device for disrupting material in a body vessel and a method for making such a device. The device includes a plurality of arms disposed circumferentially about an axis. Each arm includes two blades； one sharper, and one blunter. The sharper blades are all oriented in the same direction, clockwise or counterclockwise, such that when the device is rotated in a first direction, the sharper blades engage the material, and in the other, the duller blades engage the material.
